Wednesday, 8 October 2008

George R. Brown Convention Center, Exhibit Hall E

J. Patrick Megonigal¹, Jason Keller¹ and Pamela Weisenhorn², (1)Smithsonian Env Res Center, Smithsonian Environmental Research Center, PO Box 28 647 Contees Wharf Rd., Edgewater, MD 21037-0028
(2)Ecology, Evolution, and Behavior, University of Minnesota, 100 Ecology Bldg, 1987 Upper Buford Circle, St. Paul, MN 55108

Methanogenesis in wetland soils contributes 40% of global methane emissions to Earth’s atmosphere, making it an important microbial process that governs climate. Even though methanogens compete poorly with other heterotrophic microbes for organic carbon (i.e. electrons), they dominate freshwater wetland soils because competing microorganisms can be limited by the supply of electron accepting compounds such as Fe(III), SO₄^2- or humic substances. Thus, methane production is ultimately controlled by the supply of both electron donating compounds (organic carbon) and electron accepting compounds (inorganic or organic). Humic substances are a dominate constituent of wetland soils that can act both as electron donors and electron acceptors in anaerobic microbial respiration. Yet, their role in microbial respiration is largely unknown. Here we demonstrate, for the first time, that humic acids extracted from a variety of wetland soils alter CO₂ and CH₄ production in anaerobic lab incubations. Humic acids extracted from a variety of wetland soils behaved differently, with some serving as electron donors and others serving as electron acceptors. Our results suggest that soil-derived humic substances may be an important, and currently unexplored, control of anaerobic decomposition in wetland soils.

See more of: National Science Foundation Poster Session
See more of: Z01 SSSA-ASA-CSSA Special Programs--Invited Abstracts Only

2008 Joint Annual Meeting (5-9 Oct. 2008): Humic Acids Influence Microbial Respiration and Methanogenesis in Wetland Soils.

699-8 Humic Acids Influence Microbial Respiration and Methanogenesis in Wetland Soils.